if a network based fileserver is all you are looking for then i would suggest you to use OPEN MEDIA VAULT. it a simple os and lightweight too. works off a debian base so not too resource hungry. it should work well on your existing hardware and has a web gui interface ready for ease of control. I am using it on a dedicated HP n36l with a lot of other functionaility built in and simultaneously on a goflex net dock too... and it works just as splendid